Migraine is a highly prevalent and disabling neurological pain disorder. Calcitonin gene-related peptide (CGRP) is now strongly implicated in migraine;however, its exact role in the pathophysiology of migraine remains elusive. The long-term goal is to identify novel therapeutic targets for the management and treatment of migraine based on the scientific knowledge gained from the study of animal models. The objective of this proposal is to study the action of CGRP in vivo within the context of migraine. AIM 1. To determine the effect of genetically targeted hRAMPI expression in the central neurons versus peripheral nociceptive neurons on CGRP-induced behavior in mice. Mice that express hRAMPI throughout the central nervous system (CNS) and peripheral nervous system (PNS) exhibit light aversion and mechanical allodynia in response to CGRP administration in the CNS. I hypothesize that CGRP actions leading to migraine-like behaviors are centrally mediated in higher order neurons and not by peripheral nociceptive neurons. To test this hypothesis, light aversion and mechanical allodynia will be measured in transgenic mice in which hRAMPI expression is induced in all CNS neurons or restricted to peripheral nociceptive neurons. To confirm increased expression of CGRP receptors, CGRP binding will be assesed with autoradiography and its'induction of cAMP levels and CGRP mRNA. These results will establish that the critical site of action of CGRP in the pathophysiology of aversive and nociceptive behavior is in the CNS. AIM 2. To test the effect of virally targeted hRAMPI expression in discrete CNS regions on CGRP- induced behavior in mice. A number of subcortical regions have been implicated in transmission pathways leading to migraine. The hypothesis is that CGRP activates a limited number of subcortical regions, which are responsible for migraine-like behaviors. To test this hypothesis, stereotactic microinjections of virus will be used to induce hRAMPI expression in targeted regions based on previous clinical findings and c-Fos activation studies to be conducted. Behavior will be evaluated as described above. After identifying key regions, pathways will be identified via c-Fos activation in response to CGRP. These results will establish CGRP induced pathways or matrix of subcortical regions in the generation of these nociceptive behaviors. PUBLIC HEALTH RELEVANCE: The relevance of the proposed experiments to public health is that they will provide further understanding of how migraines work. Migraine is a very common disorder, and medicine currently lacks drugs that effectively prevent and treat migraine. By identifying important biological pathways in the brain, these studies could reveal new ways to manage and treat migraines and other headache disorders. NOTE: The critiques of individual reviewers are provided below in an essentially unedited form. These critiques were prepared prior to the review meeting and may not have been updated or revised subsequent to the discussion at the meeting. Therefore, they may not fully reflect the final opinions of the individual reviewers at the close of group discussion or the final majority opinion of the group. The Resume and Summary of Discussion above summarizes the final outcome of the group discussion.